As long as you're on version 1.5 or higher in the BIOS you should be good. If you're on 1.4 or lower, update your BIOS as the 1.5 is a BIOS update to fix an issue with the trackpad.
If you do need to update your BIOS make sure you go back to Windows and flash the original, locked BIOS before you update to the new one. Then follow the guide instructions again to unlock the new BIOS.
It could also be an issue with updating from High Sierra to Mojave. The 2 times I've installed Mojave now I've done so on a separate partition with a clean install. More than likely this isn't your issue, but it's possible.
You can test it by getting making a separate partition and install a fresh copy. That way you don't lose your current set up in case that's not the issue.